Hi, Let me share my experience.
I have 1one with i1Profiler, and Spyder3Elite.
Also I have look-up device with light D50 (5000 K), so I can check the calibration, comparing with the reference picture.
I calibrated the monitor one and other device, with the same settings.
The result was approximately the same. In both cases, the reference image matches the monitor (under standard light), with a small difference. Should take into account, that Spyder3Elite has an aperture equal to 25 mm, against 4 mm 1one (aperture - diameter of the measuring sensor). So theoretically Spyder3Elite should have a more accurate measurement of the emission light.

using I1

I calibrate my customers monitors using an i1Pro, that's better than i1Display (spectrophotometer vs colorimeter).
In case of hardware-calibrable monitors I use the software provided by the maker.
In other cases, I use xrite i1Match.